This invention relates in general to a dental composition and more specifically to a novel dental alloy and dental amalgam suitable for use in repairing carious tooth structure.
Dental amalgams made by triturating a silver-tin-copper alloy with mercury to form a coherent plastic mass that is settable in a few minutes has been in use since before the turn of the century. In the midst of today's rapidly advancing technology in the health care fields, the use of dental amalgam remains the technique of choice by the dental profession in repairing carious tooth structure.
Conventional dental amalgam alloys are comprised basically of a silver-tin alloy compound containing about 74 percent by weight silver and 26 percent by weight tin, with smaller amounts of copper and zinc, optionally replacing silver and tin. This alloy when amalgamated is not completely suitable because of deficiencies with regard to strength properties, resistance to corrosion and static flow and creep.
The advent of gas atomized spherical particle amalgam alloys brought about substantial improvement in the strength of dental amalgams, but deficiencies still remained with respect to the resistance to corrosion, static flow and creep of these alloys.
The available dental alloys that demonstrate the greatest resistance to corrosion and static creep are an admixture of two alloys. The major alloy comprises the conventional chemistry described above, and the minor alloy comprises silver with a high concentration of copper and little or no tin. These admixed alloys exhibit good resistance to corrosion and static creep, but are deficient in other physical and mechanical properties, and demonstrate broad variances in physical and mechanical properties and handling characteristics from production batch to production batch. In general most of the aforementioned alloys have a silver content of about 70 percent by weight or greater, and are therefore high cost alloys due to the high concentration of the silver which is also the most expensive element comprising the alloy.
Although the dental amalgam alloys described above have been satisfactory for use in repairing carious tooth structure, it can be seen from a discussion of some of their limitations, that there has been a continuing need in the dental profession for improved amalgam formulations which will improve on existing materials.